This invention relates to a tool which is used to adjust the front wheel camber of front-wheel drive vehicles having suspension systems which employ suspension struts of the type commonly known as "McPherson struts." Because such vehicles have no transmission hump and therefore may devote more space to passengers, and because these vehicles are lighter and more fuel efficient, they are becoming more prevalent. McPherson strut suspension systems are typically used because of the relative simplicity of such systems, and because they provide room and flexibility to accommodate the large constant-velocity joints used to transmit power from the engine to the front wheel.
McPherson strut suspension systems typically comprise a lower control arm to which the lower part of the wheel hub is rotatably attached by means of a ball joint. The upper part of the wheel hub forms the lower portion of the McPherson strut. The upper end of the McPherson strut accepts the weight of the vehicle, and a combination of a spring and a shock absorber in the upper part of the strut dampens the motion of the system to provide a smooth ride. When subjected to an excessive load, however, such as may be caused by a pothole or a curb, the strut tends to bend. In some cases, where the bend is permanent, and means must be provided to straighten or correct the bend in the strut to bring the front-end suspension system back into alignment; otherwise, strut replacement is required.
Such a means has heretofore been provided for vehicles having conventional rear wheel drive systems. In these vehicles, the McPherson strut in the front-end suspension extends nearly to the ball joint, the upper and lower portions of the wheel hub being in close proximity because no constant velocity joint is required. In these vehicles, it is possible to affix to the lug bolts of the wheel (which is supported by the wheel bearings) a tool which has at its upper end an hydraulic ram which may push or pull against the fairly long McPherson strut to bend it and thereby adjust the camber of the wheel.
In vehicles having front-wheel drive, however, the upper and lower portions of the wheel hub must be farther apart to accommodate the constant-velocity joint which transmits power from the engine to the wheel. This constant-velocity joint occupies the space where the lower portion of the McPherson strut would be in a conventional drive vehicle; therefore, in front-wheel drive vehicles, the McPherson struts must be shorter that those in vehicles having rear wheel drive. Because such struts are shorter, more force is needed to bend them for adjustment purposes than in rear-wheel drive vehicles; such force in front-wheel drive vehicles is so great that the tool mentioned above which is adequate for bending McPherson struts in rear-wheel drive vehicles by directing this force directly against the lug bolts, can ruin the wheel bearings in front-wheel drive vehicles.